1. Field of the Invention
The present invention relates generally to the field of valves, and more particularly, to an improved valve assembly for use in association with a storage tank or "cylinder" containing a gaseous fuel, such as propane or LPG.
2. Description of the Prior Art
Cylinder valves are, of course, known, and examples thereof are shown in one or more of the following issued U.S. Pat. Nos. 4,210,168; 2,415,258; 3,285,274; and 3,981,328.
Such cylinders are in widespread use today, and are generally refillable. However, when refilling fuel storge tanks through such valves, care must be taken to insure that the refilled liquid does not exceed a maximum level. The reason for this is that such refilling operations normally occur at a colder-than-ambient condition. When subsequently uncoupled from its refilling source, the liquid in the tank warms and expands. Unless there is ullage or headspace within the tank at ambient temperature, such expansion of the liquid may cause liquid to spew from a safety release valve. Otherwise the tank may rupture.
More recently, others have attempted to design cylinder valves having overfill preventing features, as shown in U.S. Pat. Nos. 3,929,155 and 4,142,552.